You may have never heard of inflammation, yet it contributes to every major chronic condition from heart disease to cancer to diabetes.

In fact, it’s widely believed that chronic inflammation plays a significant role (as either a cause or effect) in many diseases, including type 2 diabetes, autoimmune diseases, such as arthritis and Crohn’s disease, and the three top killers in the United States: heart disease, cancer and stroke. Emerging research is focusing on the link between inflammation and brain disorders, including Alzheimer’s disease and dementia. Obesity is one of the biggest drivers for inflammation—fat tissue actually produces and secretes over 100 different types of inflammatory messengers. (Losing weight, including through gastric bypass, can significantly lower inflammation markers, according to a 2011 study in the journal Surgery for Obesity and Related Diseases.) But obesity is not the only cause: “It’s clear that genetics, family history, lifestyle and stress all play a large role in inflammation,” says Christopher P. Cannon, M.D., a professor at Harvard Medical School and author of The Complete Idiot’s Guide to the Anti-Inflammation Diet.

The tricky thing with inflammation is that it sometimes has symptoms, such as pain and lethargy, but often doesn’t. You won’t know you have inflammation until you get tested. “People who are a little overweight, who have borderline high cholesterol, borderline high blood pressure—those are the people who really need to be tested now,” says Cannon. (A simple and affordable blood test ordered by your general practitioner can diagnose inflammation.) “If you find elevated markers at that point, you can really help ward off inflammation-rooted problems in the future with aggressive prevention.”